This invention relates generally to a safety device used in pools, spas, jacuzzis and other such water reservoirs, and more particularly to water circulating pumps which avoid entrapment of a person or an object that may inadvertently block the pump intake or drain.
In water reservoirs such as pools, whirlpools and spas, a water pump is provided to extract the water from the pool or spa (e.g., through a pump inlet located at the drain of the pool or spa) and to re-circulate the water back into the pool or spa through the nozzles/jets located on the side of the pool or spa, thereby creating turbulence.
Personal contact with the drain can be dangerous, painful or even fatal. A typical drain is 5 to 8 inches in diameter. When the body or hair of a person is positioned in close proximity to the drain, the body or hair may completely block the drain opening thereby creating a vacuum. If the drain is blocked, the person may be entrapped and drowned.
Commonly used recirculating water pumps if obstructed (e.g., completely blocked by the body or hair of a person) can draw a partial vacuum at the drain opening that may exert sufficient suction forces to prevent a person from pulling free of the drain. Even if the person is able to pull free of the sucking drain, bruises or welts may result. In at least one case, a young girl drowned in a hot tub when her hair was caught and sucked into the drain.
One solution to this problem is disclosed in U.S. Pat. No. 5,690,476 (Miller), whose disclosure is incorporated by reference herein. The '476 patent discloses an apparatus for automatically shutting off the pump in a water reservoir should anyone or anything obstruct the water reservoir drain. The present invention is an improvement over this apparatus by including an automatic activation of a positive pressure to assist dislodging the person or thing obstructing the water reservoir drain, as will be discussed below.
Other types of safety devices for avoiding entrapment at the pump intake are commercially available and the patent literature includes various disclosures of such safety devices.
For example, U.S. Pat. No. 4,115,878 (Johnson, et al.) discloses a spa safety drain, which does not employ any springs, valves, electrical components or moving parts of any type, for preventing entrapment at the drain.
U.S. Pat. Nos. 5,167,041 (Burkitt, III) and 5,347,664 (Hamza, et al.) disclose suction fittings for use in a water circulation system that detect blockage to disable the pump in order to prevent damage or physical injury.
U.S. Pat. No. 4,620,835 (Bell) discloses a system to protect the water pump against running dry and against blockage at the drain. This system employs a pressure sensor and pressure switches for interrupting power to the water pump.
Another system that guards against complete occlusion of the intake to a pump has been employed in heart-lung machines, as disclosed in the article by Applicant The Development of Heart-Lung Machines, Surgery, Gynecology and Obstetrics, March 1982 at 403.
While some prior art safety devices for avoiding entrapment at the pump intake may be generally suitable for their intended purposes, they nevertheless leave something to be desired for one or more of the following standpoints: safety, reliability, simplicity of construction and cost.